Some forces are planning to cut more than 30% of their non-frontline workforce in order to protect frontline numbers. Photograph: Duncan Hale-Sutton/Alamy

Police forces in England and Wales plan to lose 34,100 officers and staff over the next four years, amid fresh evidence that the cuts will trigger a rise in property crime.

The first reliable estimate by Her Majesty's Inspectorate of Constabulary is far higher than previous forecasts of 28,000 made by police staff organisations. Sir Denis O'Connor, HM chief inspector of constabulary, said the reduction in officers and staff being planned was the largest the police had faced in more than two generations.

HMIC says the 43 police forces plan to cut 16,200 officers, 1,800 police community support officers and 16,100 police staff – a reduction of 14% in the workforce. The reduction in uniformed police officers represents 11% of the 140,000 constables in the country.

A research paper published alongside the HMIC report will infuriate Home Office ministers who have been arguing there is no direct link between falling police numbers and levels of crime. The paper contradicts this by saying recent research using more robust methodologies has demonstrated a link and that a 10% fall in officers could lead to a 3% rise in property crime.

The report says 11,200 jobs – nearly one-third of the 34,100 cut – have already gone as forces make preparations to deal with a 20% cut in Whitehall funding over the next four years.

Separate Home Office figures published on Thursday show there are 4,625 fewer police officers than a year ago – a fall of 3.2% – and 5,586 fewer police staff.

"We found authorities and forces are planning relatively modest cuts to frontline numbers this year (2011/12) and they had all set an ambition to reduce crime. But whether they achieve and sustain this is yet to be seen,'' said Roger Baker of HMIC. "To sustain this, most forces will have to transform their efficiency. Those forces that start the spending review period as the most efficient and those forces that face the greatest cuts will find this the most difficult."

The 20% cut in Whitehall funding has been front-loaded with two-thirds falling over the next two years, and HMIC say it will be "very challenging to protect the frontline" over the next 18 months.

The survey estimates the total police workforce will fall from 243,900 in March 2010 to 209,800 by March 2015. Officer numbers will fall from 143,800 to 127,600 over the same period, bringing them back to levels last seen in 2001/2002.

HMIC names seven police forces that it says have the most difficult challenge in protecting the frontline. The problems facing the Greater Manchester and West Midlands forces are already well known. But the inspectors add the Devon and Cornwall, Gwent, Nottinghamshire, Sussex and West Mercia forces to the list.

The extra forces all face spending gaps of between £24m and £51m that have to be found by 2015.

The shadow home secretary, Yvette Cooper, said the report showed that damage to policing from the government's 20% cuts was worse than previously feared.

"Cutting 16,200 police officers, including 2,500 frontline officers by next year alone, is an irresponsible gamble with crime and public safety," said Cooper, adding that the reports showed the home secretary's claim that the cuts didn't need to affect frontline policing was wrong.

Returns from 42 out of the 43 police forces in England and Wales show they plan to cut frontline numbers by 2% by March next year with officers and staff in other roles falling by 11%.

But the HMIC report shows that their hopes of restricting frontline policing cuts to 2% every year between next March and 2015 will rest on a "transformation" of the rest of their working practices.

This assumes that 22 of the forces cut the rest of their workforce by at least 30% and for 10 of them the figure rises to more than 50%. HMIC agrees these assumptions may prove very optimistic.

The HMIC research paper details the evidence for a link between falling police numbers and crime rates. It acknowledges that academic evidence is divided but says the most recent studies do show a strong link between higher police numbers and lower levels of property crime, but the evidence for a link with violent crime is weaker.

The studies suggest that for every 10% fall in police numbers there will be a 3% rise in property crime, but the HMIC paper concludes that it is too early to say that such a link definitely exists and more work needs to be done.

Paul McKeever, Police Federation chairman, said the report confirmed his worst fears. "Cuts being implemented by this government will turn the clock back at least a decade by reducing police officers and police staff by over 34,000 by 2015. The knock-on effect will be police forces struggling to keep their heads above water as they try to deal with increasing demands and diminishing resources."

But the Home Office minister James Brokenshire insisted the effectiveness of a police force did not depend on total numbers, but on how well it used its resources. "The HMIC report shows the police can and are rising to the challenge by reducing costs from the back office while protecting frontline services. HMIC predict that by March 2012 the proportion of the police workforce working in frontline roles will be higher than it was in March 2010."

• This article was amended on 27 July 2011. The original subheading referred to a 3% increase in crime. The increase is for property crime only.